is the oldest of the four Vedas, originally composed in Vedic Sanskrit

If you prefer a physical book (or a high-quality digital purchase), look for:

rigveda. Format: pdf in Devanagari | ITX in ITRANS scheme | ਸਂਸ੍ਕਤ HTML in different language scripts | Information and Links. | | Sanskrit Documents Collection Rigved Mandal 1-3 | PDF | Vedas | Sikhism - Scribd Rigved Mandal 1-3 | PDF | Vedas | Sikhism.

• If published before 1926 (or the applicable public-domain cutoff in your jurisdiction) it may be public domain.
• Otherwise, look for explicit open-license (CC BY/CC0) or permission statements.

If you are looking for a complete, simplified Punjabi translation, the following printed works are often available for order: Rigveda (Translator: Gyani Jujhar Singh Azad) : This is a prominent translation published by B. Chattar Singh Jiwan Singh

If you're interested in downloading a PDF version of the Rig Veda in Punjabi, I recommend searching for reputable sources that provide accurate translations and interpretations.